1. Field of the Invention
The present invention relates to an engagement structure of a multi-polar waterproof connector and a dummy plug, where a waterproof performance between a connector housing and a plurality of wires to which terminals are respectively connected is improved and a waterproof performance of a portion of the connector housing to which a wire is not connected is improved using a dummy plug.
2. Description of the Related Art
As a dummy plug for a waterproof connector of this type, there are one shown in FIGS. 1 and 2 and disclosed-in Japanese Utility Model Application Laid-Open No. 63-50468 and one shown in FIGS. 3 and 4 and disclosed in Japanese Patent Application Laid-Open No. 7-122331.
A dummy plug A for a waterproof connector illustrated in FIGS. 1 and 2 is constituted with a core member 5 made of synthetic resin and having a shaft portion 5a and a head 5b formed in a disc stepped shape, and an almost cylindrical rubber plug 6 fitted on the shaft portion 5a of the core member 5. As illustrated in FIGS. 1 and 2, a plurality of retaining protrusions 5c are formed on the shaft portion 5a of the core member 5, and the respective retaining protrusions 5c are engaged with or retained in a recessed portion 6a formed inside the rubber plug 6.
Then, the dummy plug A is fitted in an empty terminal accommodation hole (not shown) in a connector housing of a waterproof connector (not shown), so that water is prevented from permeating the empty terminal accommodation hole. At this time, a plurality of guide portions 5d provided on the head 5b of the core member 5 abut on an inner face of the terminal accommodation hole of the connector housing so that the dummy plug A is positioned and fitted in the terminal accommodation hole. Also, when a terminal connected with a wire is accommodated in a terminal accommodation hole of the connector housing, the terminal is retained by a lance (a flexible retaining arm) not shown.
A dummy plug B for a waterproof connector illustrated in FIGS. 3 and 4 is constituted with a rubber plug 7 for sealing a wire which is fitted in an empty terminal accommodation hole 2 of a plurality of terminal accommodation holes 2 formed in a connector housing 1 of the waterproof connector in which a male terminal is not inserted and a rear holder 8 made of synthetic resin and having a shaft portion 8a having the same diameter as that of a wire 3 inserted into a wire passing-through hole 7a of the rubber plug 7.
As shown in FIG. 4, a frame-like and overhanging-shaped flexible locking portion 8b of the rear holder 8 and an engaging pawl 1a of the connector housing 1 are engaged with each other, so that the dummy plug B is fitted into the empty terminal accommodation hole 2 of the connector housing 1 which is not used and is retained therein, thereby preventing water from permeating the empty terminal accommodation hole 2 from the outside thereof.
However, the dummy plug A used for the connector housing of the conventional waterproof connector has an engagement structure where the rubber plug 6 is prevented from coming off by retaining the respective retaining protrusions 5c provided in a projecting manner on the shaft 5a of the core member 5 in the recessed portion 6a of the rubber plug 6 and the rubber plug 6 is fitted into a base end portion of the empty terminal accommodation hole of the connector housing which is not used. Therefore, a retaining or engaging force of the dummy plug A to the empty terminal accommodation hole of the connector housing is weak or poor so that the dummy plug A is apt to easily come off from the terminal accommodation hole of the connector housing.
Also, the dummy plug B used for the connector housing 1 of the conventional waterproof connector has a complicated structure where the flexible locking portion 8b provided in a projecting manner on the rear holder 8 is caused to be engaged with the engaging pawl 1a of the connector housing 1 to prevent the dummy plug B from coming off. Therefore, the entire dummy plug B is large-sized and manufacturing cost thereof is increased.
The present invention has been attained in order to solve the above problems and an object thereof is to provide an engagement structure of a multi-polar waterproof connector and a dummy plug, where an engaging force (retaining force) of a dummy plug to a connector housing is enhanced and the dummy plug can be reduced in size and its manufacturing cost can be reduced.
A first aspect of the present invention is an engagement structure of a waterproof connector and a dummy plug comprising: a connector housing having a plurality of terminal accommodation chambers formed therein, the terminal accommodation chambers being chambers into which a terminal connected with a wire is to be inserted, the connector housing further having a plurality of rubber plug accommodation recesses formed therein, the rubber plug accommodation recesses being formed at positions opposed to the terminal accommodation chambers, the connector housing having one wall portion at an end opposed to the terminal accommodation chambers, and the one wall portion having wire insertion and passing-through holes through which the wire is respectively inserted to pass; rubber plugs respectively inserted forcibly into the plurality of rubber plug accommodation recesses, the rubber plugs being respectively formed with wire insertion and passing-through holes through which the wire is respectively inserted to pass; and a dummy plug sealing one of the wire insertion and passing-through holes of the plurality of rubber plugs, the dummy plug having a shaft portion which is inserted into the wire insertion and passing-through hole of the rubber plug to seal the wire insertion and passing-through hole of the rubber plug, the dummy plug further having at its one end a flange portion, and the shaft portion having engaging protrusions; wherein, when the wire is inserted to pass through the wire insertion and passing-through hole of one rubber plug of the plurality of rubber plugs and one of the wire insertion and passing-through holes formed in the one wall portion, the rubber plug seals the terminal accommodation chamber and the wire; wherein, when the wire is not inserted to pass through the wire insertion and passing-through hole of the other rubber plug of the plurality of rubber plugs and the other wire insertion and passing-through hole formed in the other wall portion, the dummy plug is inserted to pass through the wire insertion and passing-through hole of the other rubber plug and the other wire insertion and passing-through hole formed in the other wall portion, whereby the wire insertion and passing-through hole of the other rubber plug is sealed by the shaft portion of the dummy plug; and wherein a portion of the other wall portion around the other wire insertion and passing-through hole of the other wall portion is sandwiched between the flange portion of the dummy plug and the engaging protrusion of the dummy plug.
In the engagement structure of a waterproof connector and a dummy plug of the first aspect, when the shaft portion of the dummy plug is inserted from the wire insertion and passing-through hole of the one wall portion of the connector housing into the wire insertion and passing-through hole of the rubber plug into which a wire is not inserted, a portion of the wire insertion and passing-through hole of the one wall portion is retained so as to be sandwiched between the engaging protrusions of the shaft portion and the flange portion thereof, so that a retaining or engaging force of the dummy plug to the connector housing is improved.
A second aspect of the invention is an engagement structure of a waterproof connector and a dummy plug according to the first aspect, wherein the engaging protrusion of the dummy plug is accompanied with other engaging protrusions, the plurality of engaging protrusions are formed on a peripheral face of the shaft portion of the dummy plug in a projecting manner, and the plurality of engaging protrusions are positioned at equal intervals; wherein the plurality of engaging protrusions are formed integrally with the shaft portion; wherein the diameter of the flange portion of the dummy plug is larger than that of the other wire insertion and passing-through hole of the other wall portion; wherein the flange portion is formed integrally with the shaft portion; and wherein a gap between each of the engaging protrusions and the flange portion is approximately equal to the thickness of the one wall portion.
In the engagement structure of a waterproof connector and a dummy plug of the second aspect, such a simple structure can be obtained where the plurality of engaging protrusions and the flange portion are formed on the shaft portion of the dummy plug with a distance spaced from each other so as to be approximately equal to the thickness of the one wall portion of the connector housing, which results in size-reduction of the entire dummy plug and reduction in manufacturing cost of the same.
A third aspect of the invention is an engagement structure of a waterproof connector and a dummy plug according to the second aspect, wherein each of the engaging protrusions of a width direction is formed in a general triangular shape, and is constituted with an engaging face positioned at the flange portion side and an inclining face positioned at a side of a distal end of the shaft portion; wherein the inclining face positioned at the distal end side of the shaft portion is formed at a slant inclination angle; and wherein the engaging face of the flange portion side is formed at a predetermined engaging angle.
In the engagement structure of a waterproof connector and a dummy plug of the third aspect, the respective engaging protrusions of the shaft portion of the dummy plug are smoothly engaged with, or retained in, the wire insertion and passing-through hole of the one wall portion of the connector housing through moderately inclining faces of the respective generally triangular engaging protrusions, in side view, of the shaft portion of the dummy plug positioned at a distal end side of the shaft portion, and the engaged or retained state thus obtained is securely maintained with the engaging or retaining faces of the respective engaging protrusions positioned at the flange portion side. Thereby, the wire insertion and passing-through hole of the rubber plug into which the wire is not inserted for pass-through is closed and sealed by the shaft portion of the dummy plug, so that water can be prevented from entering from the outside and a waterproof performance of the rubber plug can reliably be secured.